Effect of Calcination Temperature on Pozzolanic Reaction of Calcined Shale Mortar

摘要

This study investigated the influence of calcination temperature on the pozzolanic activity of shale. Calcination temperatures of 500°C, 600°C, 700°C, 800°C, and 900°C were used. The calcined shale powder was then passed through a No.200 sieve before being used to replace 20% of the cement in standard mortar samples. X-ray fluorescence spectrometery (XRF) was used to analyze the chemical composition of the calcined shale. In addition, the effects of replacing mortar with calcined shale were also examined with regard to setting time, pozzolanic activity, compressive strength, ultrasonic wave velocity, and the water absorption of the mortar. The test results demonstrate that the chemical composition of SiO_2+Al_2O_3+Fe_2O_3 exceeded the 70% required by ASTM C618 specifications. The strength activity index (SAI) of calcined shale at 7, 28, 56 days exceeded 75%. At 28 days, the SAI values of samples produced with shale calcined at 700°C and 800°C exceeded 99%. After 28 days, the SAI, water absorption, and ultrasonic wave velocity values were nearly identical to those of control samples produced using only cement. Among all shale samples, those calcined at temperatures between 700 and 800°C demonstrated the highest pozzolanic activity.